GUIDE FOR THE DESIGN OF CRANE-SUPPORTING STEEL STRUCTURES

SECOND EDITION

R.A. MACCRIMMON

NIAGARA FALLS, ONTARIO

Canadian Institute of Steel Construction Institut canadien de la construction en acier

3760 14th Avenue, Suite 200 Markham, Ontario L3R 3T7

Copyright 2009

by

Canadian Institute of Steel Construction

All rights reserved. This book or any part thereof must not be reproduced

in any form without the written permission of the publisher.

Second EditionFirst Printing, December 2007

Second Revised Printing, January 2009Third Printing, August 2009

Fourth Revised Printing, February 2010Fifth Revised Printing, July 2012

ISBN 978-0-88811-132-6

PRINTED IN CANADA

iii

TABLE OF CONTENTS

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

PREFACE TO THE SECOND EDITION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

CHAPTER 1 - INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

CHAPTER 2 - LOADS

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.2 Symbols and Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3.2 Vertical Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3.3 Side Thrust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3.4 Traction Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3.5 Bumper Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3.6 Vibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . . . . 6

2.4.1 Fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.4.2 Ultimate Limit States of Strength and Stability . . . . . . . . . . . . . . . . . . . . . . . . . 7

CHAPTER 3 - DESIGN FOR REPEATED LOADS

3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2 Exclusion for Limited Number of Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.3 Detailed Load-Induced Fatigue Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.3.2 Palmgren-Miner Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3.3.3 Equivalent Stress Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3.3.4 Equivalent Number of Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.3.5 Fatigue Design Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.4.3 Number of Full Load Cycles Based on Class of Crane . . . . . . . . . . . . . . . . . . . . . 14

3.4.4 Fatigue Loading Criteria Based on Duty Cycle Analysis . . . . . . . . . . . . . . . . . . . . 16

3.4.5 Preparation of Design Criteria Documentation . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.4.5.1 Fatigue Criteria Documentation Based on Duty Cycle Analysis . . . . . . . . . . . . . 17

iv

3.4.5.2 Criteria Documentation Based on Class of Crane Service (Abbreviated Procedure) . . . 18

3.5 Examples of Duty Cycle Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3.5.1 Crane-Carrying Steel Structures Structural Class of Service SA, SB, SC . . . . . . . . . . . . 18

3.5.2 Crane-Carrying Steel Structures Structural Class of Service SD, SE, SF . . . . . . . . . . . . 19

CHAPTER 4 - DESIGN AND CONSTRUCTION MEASURES CHECKLIST

4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.2 Comments on the Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

CHAPTER 5 - OTHER TOPICS

5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.2 Crane-Structure Interaction in Mill or Similar Buildings . . . . . . . . . . . . . . . . . . . . . . . 32

5.3 Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.4 Methods of Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.5 Notional Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.6 Segmented Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.7 Building Longitudinal Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.8 Building Expansion Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5.9 Mono-symmetric Crane Runway Beams, Lateral-Torsional Buckling . . . . . . . . . . . . . . . . 34

5.9.1 Design Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.10 Biaxial Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

5.11 Heavy Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.12 Intermediate Web Stiffeners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.13 Links to Crane Runway Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.14 Bottom Flange Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.15 Attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.16 End Stops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.17 Unequal Depth Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.18 Underslung Cranes and Monorails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.19 Jib Cranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.20 Truss Type Crane Runway Supports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.21 Column Bases and Anchor Rods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.22 Dissimilar Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.23 Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.24 Rail Attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.25 Outdoor Crane Runways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

v 5.26 Seismic Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.27 Standards for Welding for Structures Subjected to Fatigue . . . . . . . . . . . . . . . . . . . . . . 41

5.28 Erection Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5.29 Standards for Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5.30 Maintenance and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

CHAPTER 6 - REHABILITATION AND UPGRADING OF EXISTING CRANE-CARRYING STEEL

STRUCTURES

6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.2 Inspections, Condition Surveys, Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.3 Loads, Load Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6.4 Structural Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6.5 Reinforcing, Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

6.5.1 Reinforcing an Existing Runway Beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

6.5.2 Reinforcing an Existing Column . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

6.5.3 Welding to Existing Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

CHAPTER 7 - SUGGESTED PROCEDURE FOR DESIGN OF CRANE RUNWAY BEAMS

7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

7.2 Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

7.3 Design Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

APPENDIX A - DESIGN EXAMPLES

Design Example 1 Illustration of Design of a Mono-symmetric Section Crane Runway Beam . . . . . . . . . . . . . . . . 80

Design Example 2 Illustration of Design of a Heavy-Duty Plate Girder Type Crane Runway Beam . . . . . . . . . . . . . 95

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122

vi

FOREWORD

The Canadian Institute of Steel Construction is a national industry organization representing the structural steel, open-web steel joist and steel plate fabricating industries in Canada. Formed in 1930 and granted a Federal !" # $

fabricated steel in construction.

As a member of the Canadian Steel Construction Council, the Institute has a general interest in all uses of steel in construction. CISC works in close co-operation with the Steel Structures Education Foundation (SSEF) to develop educational courses and programmes related to the design and construction of steel structures. The CISC supports and actively participates in the work of the Standards Council of Canada, the Canadian Standards Association, the Canadian Commission on Building and Fire Codes and numerous other organizations, in Canada and other countries, involved in research work and the preparation of codes and standards.

Preparation of engineering plans is not a function of the CISC. The Institute does provide technical information through its professional engineering staff, through the preparation and dissemination of publications, and through the medium of seminars, courses, meetings, video tapes, and computer programs. Architects, engineers and others interested in steel construction are encouraged to make use of CISC information services.

This publication has been prepared and published by the Canadian Institute of Steel Construction. It is an important part of a continuing effort to provide current, practical, information to assist educators, designers, fabricators, and others interested in the use of steel in construction.

Although no effort has been spared in an attempt to ensure that all data in this book is factual and that the numerical values are accurate to a degree consistent with current structural design practice, the Canadian Institute of Steel Construction, the author and his employer, Hatch, do not assume responsibility for errors or oversights resulting from the use of the information contained herein. Anyone making use of the contents of this book assumes all liability arising from such use. All suggestions for improvement of this publication will receive full consideration for future printings.

CISC is located at

3760 14th Avenue, Suite 200 Markham, Ontario, L3R 3T7

and may also be contacted via one or more of the following:

Telephone: 905-946-0864 Fax: 905-946-8574 Email: info@cisc-icca.ca Website: www.cisc-icca.ca

Revisions This Edition of the Design Guide supersedes all previous versions posted on the CISC website: www.cisc-icca.ca. Future revisions to this Design Guide will be posted on this website. Users are encouraged to visit this website periodically for updates.

vii

PREFACE TO THE SECOND EDITION

%&''*"&

comments along with questions, answers to which could generate more information for the designer of these structures.

+&"/;

? K Kincludes an index.

> K Q ?North American practice.

The author wishes to thank all those who took the time to comment and provide suggestions. Special thanks to the late David Ricker (reference 27) who took the time to constructively comment in depth, providing a number of suggestions which have been incorporated into this edition.

viii

1CHAPTER 1 - INTRODUCTION

>

steel structures that is compatible with Canadian codes and standards written in Limit States format. It is intended to be used in conjunction with the National Building Code of Canada, 2010 (NBCC 2010), and Canadian Standards Association (CSA) Standard S16-09, Limit States Design of Steel Structures (S16-09). Previous editions of these &

detail.

While many references are available as given herein, they do not cover loads and load combinations for limit

&K

+;[\]+

+guide provides information on how to apply the current Canadian Codes and Standards to aspects of design of crane-supporting structures such as loads, load combinations, repeated loads, notional loads, mono-symmetrical sections, analysis for torsion, stepped columns, and distortion-induced fatigue.

The purpose of this design guide is twofold: 1. To provide the owner and the designer with a practical set of guidelines, design aids, and references that can

be applied when designing or assessing the condition of crane-supporting steel structures. 2. To provide examples of design of key components of crane-supporting structures in accordance with:

(a) loads and load combinations that have proven to be reliable and are generally accepted by the industry, (b) the recommendations contained herein, including NBCC 2010 limit states load combinations, (c) the provisions of the latest edition of S16-09, and, (d) duty cycle analysis.

The scope of this design guide includes crane-supporting steel structures regardless of the type of crane. The interaction of the crane and its supporting structure is addressed. The design of the crane itself, including jib "&""^"&_&such as those published by the CMAA.

Design and construction of foundations is beyond the scope of this document but loads, load combinations, ?K`information see Fisher (2004).

#

"&]++

+;

"

Table 3.1. Design for fatigue is often not required for Classes A and B but is not excluded from consideration.

The symbols and notations of S16-09 are followed unless otherwise noted. Welding symbols are generally in accordance with CSA W59-03.

The recommendations of this guide may not cover all design measures. It is the responsibility of the designer of the crane-supporting structure to consider such measures. Comments for future editions are welcome.

The author wishes to acknowledge the help and advice of Hatch, for corporate support and individual assistance of colleagues too numerous to mention individually, all those who have offered suggestions, and special thanks to Gary Hodgson, Mike Gilmor and Laurie Kennedy for their encouragement and contributions.

2CHAPTER 2 - LOADS

2.1 GeneralBecause crane loads dominate the design of many structural elements in crane-supporting structures, this guide

Q

/;''The crane loads are considered as separate loads from the other live loads due to use and occupancy and environmental effects such as rain, snow, wind, earthquakes, lateral loads due to pressure of soil and water, and temperature effects because they are independent from them.

Of all building structures, fatigue considerations are most important for those supporting cranes. Be that as it may, &&^&then check for the fatigue and serviceability limit states. For the ultimate limit states, the factored resistance may allow yielding over portions of the cross section depending on the class of the cross-section as given in Clause ['!+

[['!"|the load that is likely to be applied repeatedly. The fatigue resistance depends very much on the particular detail

[K}K""&?

Crane loads have many unique characteristics that lead to the following considerations:(a) An impact factor, applied to vertical wheel loads to account for the dynamic effects as the crane moves and

?^(b) For single cranes, the improbability of some loads, some of short duration, of acting simultaneously is

considered.(c) For multiple cranes in one aisle or cranes in several aisles, load combinations are restricted to those with a

reasonable probability of occurrence.(d) Lateral loads are applied to the crane rail to account for such effects as acceleration and braking forces of

the trolley and lifted load, skewing of the travelling crane, rail misalignment, and not picking the load up vertically.

(e) Longitudinal forces due to acceleration and braking of the crane bridge and not picking the load up vertically are considered.

(f) Crane runway end stops are designed for possible accidental impact at full bridge speed.(g) Certain specialized classes of cranes such as magnet cranes, clamshell bucket cranes, cranes with rigid masts

(such as under hung stacker cranes) require special consideration.This guide generally follows accepted North American practice that has evolved from years of experience in the design and construction of light to moderate service and up to and including steel mill buildings that support overhead travelling cranes (AISE 2003, Fisher 2004, Griggs and Innis 1978, Griggs 1976). Similar practices, widely used for other types of crane services, such as underslung cranes and monorails, have served well (MBMA 2006). The companion action approach for load combinations as used in the NBCC 2005, and similar to that in ASCE (2002), is followed.

2.2 Symbols and NotationThe following symbols and nomenclature, based on accepted practice are expanded to cover loads not given in Part 4 of the NBCC 2010. The symbol, L, is all the live loads excluding loads due to cranes. The symbol C means a crane load. Cvs - vertical load due to a single crane Cvm - vertical load due to multiple cranes Css - side thrust due to a single crane Csm - side thrust due to multiple cranes Cis - impact due to a single crane

3 Cim - impact due to multiple cranes Cls - longitudinal traction due to a single crane in one aisle only Clm - longitudinal traction due to multiple cranes Cbs - bumper impact due to a single crane Cd - dead load of all cranes, positioned for maximum seismic effects D - dead load E - earthquake load (see Part 4, NBCC 2010) H - load due to lateral pressure of soil and water in soil L

&"&&&K

such as the pick up of a maximum load near one end of the bridge, traversing to the centre of the bridge while travelling along the length of the runway, releasing most of the load and travelling back for another load. This is sometimes the case in steel mills and foundries. On the other hand, the operation may be random as in warehousing operations. Weaver (1985) provides examples of duty cycle analyses albeit more appropriate for crane selection than for the supporting structure.

&

loading as shown in Table 2.1. These are based on North American practice (Fisher 2004, Griggs and Innis 1978, Rowswell 1987). Other jurisdictions, e.g., Eurocodes, have similar but different factors. In addition to these, load +&

AISE (2003) notes that some of the recommended crane runway loadings may be somewhat conservative. This is deemed appropriate for new mill type building design where the cost of conservatism should be relatively low. However when assessing existing structures as covered in Chapter 6, engineering judgment should be applied judiciously as renovation costs are generally higher. See AISE (2003), CMAA (2010), Griggs (1976), Millman (1991) and Weaver (1985) for more information.

2.3.2 Vertical LoadsImpact, or dynamic load allowance, is applied only to crane vertical wheel loads, and is only considered in the design of runway beams and their connections. Impact is factored as a live load. AISE Report No. 13 recommends that impact be included in design for fatigue, as it is directed to the design of mill buildings. For most applications, this is thought to be a conservative approach. Following Rowswell (1978) and Millman (1996) impact is not included in design for fatigue.

For certain applications such as lifting of hydraulic gates, the lifted load can jamb and without load limiting devices, the line pull can approach the stalling torque of the motor, which may be two to three times the nominal crane lifting capacity. This possibility should be made known to the designer of the structure.

4Table 2.l

!"

Crane Typea

Vertical Load #

Impact$!% Tractive Forcei

&'(( Wheel Loadb !

c

Combined )!

!c and Trolley

Combined )!

!c and Crane

)

&'(( Load on Driven Wheels

Cab Operated or Radio Controlled

125 40d 20e 10d 20

Clamshell Bucket and Magnet Cranesf

125 100 20 10 20

Guided Arm Cranes, Stacker Cranes

125 200 40g 15 20

Maintenance Cranes 120 30

d 20 10d 20

Pendant Controlled Cranesj

110 20 10 20

Chain Operated Cranesh 105 10 10

Monorails 115 10 10

*%

(a) Crane service as distinct from crane type is shown in Section 3.4.2.

(b) Occurs with trolley hard over to one end of bridge.

(c) Lifted load includes the total weight lifted by the hoist mechanism but unless otherwise noted, not including the column, ram, or other material handling device which is rigidly guided in a vertical direction during hoisting.

(d) Steel mill crane service (AISE 2003).

(e) This criterion has provided satisfactory service for light (see Table 3.1) to moderate duty applications and is consistent with the minimum requirements of the NBCC 2010.

(f) Severe service as in scrap yards and does not include magnet cranes lifting products such as coils and plate in a warehousing type operation.

(g) Lifted load includes rigid arm. The rigid arm contributes to side thrust.

(h) Because of the slow nature of the operation, dynamic forces are less than for a pendant controlled cranes.

(i) The maximum load on the driven wheels is applied to each rail simultaneously.

(j) For bridge speeds not exceeding 0.8 m/sec

5#"K&load. Historically, information provided on weights of crane components, particularly trolleys, has been rather unreliable and therefore is not necessarily covered by the commonly used dead load factor. Caution should be

Q

&"K&K

Crane manufacturers provide information on maximum wheel loads. These loads may differ from wheel to wheel, depending on the relative positions of the crane components and the lifted load. The designer usually has to determine the concurrent wheel loads on the opposite rail from statics, knowing the masses of the unloaded crane, the trolley, the lifted load, and the range of the hook(s) (often called hook approach) from side to side. See Figure 4. Note that minimum wheel loads combined with other loads such as side thrust may govern certain aspects of design. Foundation stability should be checked under these conditions.

2.3.3 Side Thrust Crane side thrust is a horizontal force of short duration applied transversely by the crane wheels to the rails. ` K&"&&?K

#K

?""&"Zsatisfactory service and safety. For more information see CMAA (2010) and Weaver (1985). For underslung ?

acceleration or braking of the crane trolley(s) trolley impact with the end stop non-vertical hoisting action skewing or crabbing of the crane as it moves along the runway misaligned crane rails or bridge end trucks

The effect of the side thrust forces are combined with other design loads as presented subsequently. Side thrust (total side thrust from Table 2.1) is distributed to each side of the runway in accordance with the relative lateral stiffness of the supporting structures. For new construction it is assumed that the cranes and supporting structures K"&&"unaccounted-for forces and consequential serious damage.

Side thrust from monorails is due only to non-vertical hoisting action and swinging; therefore, the values in Table 2.1 are less than those for bridge cranes.

The number of cycles of side thrust is taken as one-half the number of vertical load cycles because the thrust can be in two opposite directions.

More information can be found in AISE (2003), CMAA (2010), Fisher (2004), Griggs and Innis (1978), Griggs (1976), Millman (1996), Rowswell (1987), and Tremblay and Legault (1996).

2.3.4 Traction Load Longitudinal crane tractive force is of short duration, caused by crane bridge acceleration or braking. The locations K

#K

^K"^tractive force as 10% of the total wheel loads.

2.3.5 Bumper Impact This is a longitudinal force exerted on the crane runway by a moving crane bridge striking the end stop. The NBCC ''&

""should be reviewed by the structure designer. Following AISE (2003), it is recommended that it be based on the full rated speed of the bridge, power off. Because it is an accidental event, the load factor is taken as 1.0.

2.3.6 Vibrations Although rarely a problem, resonance should be avoided. An imperfection in a trolley or bridge wheel could set up undesirable forcing frequencies.

6`YKK

72.4.1 Fatigue The calculated fatigue stress range at the detail under consideration, to meet the requirements of Clause 26 of S16-09 and as described in Chapter 3 of this document, will be taken as that due to C1.

Note: Dead load is a steady state and does not contribute to the stress range. However, the dead load stress may cause the stress range to be entirely in compression and therefore favourable or wholly or partly in tension and therefore unfavourable.

2.4.2 Ultimate Limit States of Strength and Stability In each of the following inequalities, for load combinations with crane loads, the factored resistance, R, and the effect of factored loads such as 0.9D, are expressed in consistent units of axial force, shear force or moment acting on the member or element of concern. The most unfavourable combination governs.

Case Principal Loads Companion Loads

1. R D2. R

8CHAPTER 3 - DESIGN FOR REPEATED LOADS

3.1 General >K

&

the repetitive loading caused by cranes. Steel structures that support cranes and hoists require special attention to the design and the details of construction in order to provide safe and serviceable structures, particularly as related to fatigue. The fatigue life of a structure can be described as the number of cycles of loading required ^`"

X`(1976), Kulak and Grondin (2009), Fisher, Kulak and Smith (1997), Fisher and Van de Pas (2002), Millman (1996), Reemsnyder and Demo (1998) and Ricker (1982).

The vast majority of crane runway beam problems, whether welded or bolted, are caused by fatigue cracking of welds, bolts and parent metal. Problems have not been restricted to the crane runway beams, however. For example, trusses or joists that are not designed for repeated loads from monorails or underslung cranes have `

"Qstructural components and details that are subjected to repeated loads to ensure the structure has adequate fatigue resistance. Members to be checked for fatigue are members whose loss due to fatigue damage would adversely affect the integrity of the structural system.

As given in S16-09, Clause 26, the principal factors affecting the fatigue performance of a structural detail are considered to be the nature of the detail, the range of stress to which the detail is subjected, and the number of cycles of a load. The susceptibility of details to fatigue varies and, for convenience, Clause 26, in common with ZKK"`&the relationship between the allowable fatigue stress range of constant amplitude and the number of cycles of loading is given. These are the S-N (stress vs. number of cycles) curves.

Two methods of assessing crane-supporting structures for fatigue have developed. Historically, at least for

K&&

"

K

&&as related to the crane service. Section 3.4.1 covers this. While this has worked reasonably well, this approach has two shortcomings. First, the number of cycles, by pigeon-holing the structure, may be set somewhat too high as related to the service life of the structure in question, and second, only the maximum stress range is considered. The second, more recent, approach is to assess the various ranges of stress and corresponding numbers of cycles to which the detail is subjected and to try to determine the cumulative effect using the Palmgren-Miner rule as given in Section 3.3.2. This can be advantageous, especially in examining existing structures.

The assessment of the number of cycles nN requires care as an element of the structure may be exposed to fewer or more repetitions than the number of crane lifts or traverses along the runway. For example, if out-of-plane QK&KK?&K"&K

&crane passages N where n is the number of wheels on the rail, per crane. Also, for short-span crane runway beams depending on the distances between the crane wheels, one pass of the crane can result in more than one loading cycle on the beam, particularly if cantilevers are involved. On the other hand, when the crane lifts and traverses are distributed among several bays, a particular runway beam will have fewer repetitions than the number of lifts. For additional discussion of crane-structure interaction, see Section 5.2.

The provisions here apply to structures supporting electrically operated, top running, overhead travelling cranes (commonly referred to as EOTs), underslung cranes, and monorails. Light-duty crane support structures, where components are subjected to not more than 20 000 cycles of repeated load and where high ranges of stress in fatigue susceptible details are not present, need not be designed for fatigue.

It is necessary to evaluate the effect of repeated crane loadings before concluding that fewer than 20 000 cycles of loading will occur. Referring to Table 3.3 and 3.4, and Section 3.4.3, even supporting structures for Crane Service

+ZK''''&

/'!(*(,!0Clause 26.3.5 of S16-09 presents the situation when the number of stress range cycles of loading is limited and fatigue is therefore not likely to be a problem. First, fatigue-sensitive details with high stress ranges, likely with

9stress reversals, are excluded from these provisions and should be investigated for fatigue in any case. Second, the requirements of Clause 26.1 that the member and connection be designed, detailed, and fabricated to minimize stress concentrations and abrupt changes in cross section are to be met. Only then, if the number of cycles is less than the greater of two criteria, 20 000 or fsr3c is no fatigue check required. The detail category may determine the limit. For example, for detail category E, from Table 10, the fatigue life constant, = 361 109 MPa and, say, calculations give a fatigue stress range, sr = 210 MPa . Hence the second criterion yields a limit of 39 000 cycles. Therefore, the limit of 39 000 cycles controls and if the detail is subject to fewer than 39 000 cycles, no fatigue check is necessary.

8#9

(

3.3.1 General Clause 26.3.2 of S16-09 gives the design criterion for load-induced fatigue as follows:

Fsrsr

where

sr = calculated stress range at the detail due to passage of the fatigue load

Fsr = fatigue resistance

F/

srt

1 3

$=hcM

e o = fatigue life constant, see Clause 26.3.4 number of stress range cycles at given detail for each application of load

N = number of applications of load Fsrt = constant amplitude threshold stress range, see Clauses 26.3.3 and 26.3.4.Above the constant amplitude fatigue threshold stress range, the fatigue resistance (in terms of stress range) is considered to vary inversely as the number of stress range cycles to the 1/3 power. Rearranging the expression for the fatigue resistance, the number of cycles to failure is:

N Fsr3=h c

Accordingly the number of cycles to failure varies inversely as the stress range to the third power. Below the constant amplitude fatigue threshold stress range, the number of cycles to failure varies inversely as the stress K

The effect of low stress range cycles will usually be small on crane-supporting structures but should be investigated nonetheless. It requires the addition of a second term to the equivalent stress range (see Section 3.3.3) where the value of m is 5 for the relevant low stress range cycles. As stated in Section 2.4, a dead load is a steady state and does not contribute to stress range. However, the dead load stress may cause the stress range to be entirely in compression and therefore favourable or wholly or partly in tension and therefore unfavourable. In this regard, web members of trusses subjected to live load compressive stresses may cycle in tension when the dead load stress is tensile. This condition may also apply to cantilever and continuous beams. On the other hand, the compressive stresses due to dead load in columns may override the tensile stresses due to bending moments.

For additional information on analysis of stress histories where complex stress variations are involved, see Fisher, Kulak and Smith (1997), and Kulak and Grondin (2009).

10

3.3.2 Palmgren -Miner Rule The total or cumulative damage that results from fatigue loading, not applied at constant amplitude, by S16-09 must satisfy the Palmgren-Miner Rule:

.N

N1 0

fi

i #h_ i> H!

where:

Ni

h_ i = number of expected stress range cycles at stress range level i. N = number of cycles that would cause failure at stress range i.In a typical example, the number of cycles at load level 1 is 208 000 and the number of cycles to cause failure at load level 1 is 591 000. The number of cycles at load level 2 is 104 000 and the number of cycles to cause failure at load level 2 is 372 000. The total effect or damage of the two different stress ranges is

3.3.3 Equivalent Stress Range The Palmgren-Miner rule may also be expressed as an equivalent stress range.

e i im

1m

=v a vD D8 B! where:

evD = the equivalent stress range

ia = Nfii

hM_ i

ivD = the stress range level i. m = 3 for stress ranges at or above the constant amplitude threshold stress range. For stress ranges below the threshold, m = 5.For example, if the stress range at level 1 in the above example is 188 MPa and the stress range at level 2 is 219 MPa, then the equivalent stress range is

MPa312 000208 000 188

312 000104 000 219 2003 3

13

.+c ^ c ^m h m h< F

A calculation of the number of cycles to failure (see Section 3.3.1) and where 3 930109 gives 491 000 cycles. Since the actual number of cycles is 312 000, the percentage of life expended (damage) is 312 000/491 000) 100% = 64%. This is essentially the same result as in 3.3.2 (equivalent stress range was rounded off).

. < . OK591000208 000

372 000104 000 0 63 1 0+ =

11

3.3.4 Equivalent Number of Cycles `K&"

considering that: (1) the detail has a unique fatigue life constant as listed in Table 10 of S16-09, (2) the stress range is proportional to the load, (3) the number of cycles at the detail, nN, is proportional to the number of cycles of load on the crane

runway beam, N, (4) above and below the constant amplitude fatigue threshold stress range the number of cycles to failure

varies inversely as the stress range to the 3rd and 5th power, respectively. The equivalent number of cycles at the highest stress range level, Ne ,where Nm is the number at the highest stress range level, for cycles above the constant amplitude fatigue threshold stress range, is

/N N C Cm i i m 3+ ^ h8 B!

where Cm and Ci are the respective proportional constants of the stress ranges at the maximum stress range level and the stress range level, respectively, to the crane-induced load. For cycles below the constant amplitude fatigue

"

?"*/]&&below the constant amplitude fatigue threshold stress range do cause fatigue damage, albeit at a reduced rate.

For the example in Section 3.3.3, the equivalent number of cycles at the highest stress range level is

104 000 + 208 000 (188/219)3 = 104 000 + 131 584 = 235 584 cycles

A calculation of the number of cycles to failure (see Section 3.3.1) and where = 3930109 gives 374 160 cycles. The percentage of life expended (damage) is (235 584 / 374 160) 100% = 63%. This is the same result as in Section 3.3.2.

This approach is useful for relating duty cycle information to class of service and can be used to simplify calculations as shown in Section 3.5 and Appendix A, Design Example 2.

3.3.5 Fatigue Design Procedure The recommended procedure for design for fatigue is as follows:

Choose details that are not susceptible to fatigue. ]$?K& Avoid unaccounted-for restraints. Avoid abrupt changes in cross section. Minimize range of stress where practicable. Account for eccentricities of loads such as misalignment of crane rails. Examine components and determine fatigue categories. Calculate stress ranges for each detail. Calculate fatigue lives for each detail. Compare the fatigue life of the details to the results obtained from the detailed load-induced fatigue

assessment. Adjust the design as necessary to provide adequate resistance to fatigue

12

+

!

3.4.1 General >"K&information, usually in the form of a duty cycle analysis or results thereof. While the structure designer may provide input to a duty cycle analysis, the basic time and motion analysis should be done by plant operations personnel. A duty cycle analysis of interest to the structure designer should yield the spectrum of loading cycles for the structure taking into account such items as:

| "

"| &"&"| &K&

bridge of the crane(s). The number of cycles of loading, by load level, can therefore be determined for the critical location and for all other elements of the structure.

In the past it was somewhat common for designers to classify the structure based on ranges of number of cycles at full load. In some references (Fisher 2004, AISE 2003, CMAA 2010, MBMA 2006) this was associated with a "loading condition". Some of these references (Fisher 2004, Fisher and Van de Pas 2002, and MBMA 2006) provide information on relating the loading condition to class of crane service. A duty cycle analysis was done to the extent required to assess which of several loading conditions was most suitable.

New fatigue provisions are based on working with actual numbers of cycles and require consideration of cumulative fatigue damage. Therefore the loading condition concept is no longer recommended, and is used only for reference.

In order that the designer can determine N for all structural elements subject to fatigue assessment, the design criteria should contain a statement to the effect that cycles refers to crane loading cycles N.

K

&K"

[['!*'Kowners to specify a service life span of less than 50 years.

This section of the guide provides methods of classifying the crane-supporting structure, describes preparation of the structure design criteria for fatigue, and describes fatigue design procedure.

+;[\![

&

]+

+

13

>

based on the frequency of use of the crane and the percentage of the lifts at or near rated capacity. :

9;,0#!;=This covers cranes used in repair shops, light assembly operations, service buildings, light warehousing, or similar duty, where service requirements are light and the speed is slow. Loads may vary from no load to occasional full-rated loads, with 2 - 5 lifts per hour.

:

;&=This covers cranes used in machine shops or paper mill machine rooms, or similar duty, where service requirements are moderate. The cranes will handle loads that average 50% of the rated capacity, with 5 -10 lifts/hour, with not over 50% of the lifts at rated capacity.

:

8;?0=This covers cranes that may be used in heavy machine shops, foundries, fabricating plants, steel warehouses, container yards, lumber mills, or similar duty, and standard-duty bucket and magnet operations where heavy-duty production is required. Loads approaching 50% of the rated capacity are handled constantly during the working period. High speeds are desirable for this type of service, with 10 - 20 lifts/hour, with not over 65% of the lifts at rated capacity.

:

/;=This requires cranes capable of handling loads approaching the rated capacity throughout their life. Applications may include magnet, bucket, and magnet/bucket combination cranes for scrap yards, cement mills, lumber mills, fertilizer plants, container handling, or similar duty, with 20 or more lifts/hour at or near the rated capacity.

:

;= This requires cranes capable of handling loads approaching rated capacity continuously under severe service conditions throughout their life. Applications may include custom-designed specialty cranes essential to performing the critical work tasks affecting the total production facility. These cranes must provide the highest reliability, with special attention to ease-of-maintenance features.

>"?

&

"&

>

14

For example, if from 100 000 lifts, 10 000 are at full capacity, 70 000 are at 30% of capacity, and 20 000 are at 10% of capacity, then:

. . . . . . .k 1 0 0 1 0 3 0 7 0 1 0 2 0 4923 3 33 # # #= + + =

>K

/necessarily describe the crane-carrying structure.

Table 3.1

,

@

kJ&/!! Load Factor

Use

#occasional

!Q ,0

periods

"

!

intermittent operation

"

in

operation

"

in severe

operation

'* A* B* C D

0.531 < k'[\ B* C* D E

0.671 < k '* C D D F

0.85 < k '' D E F F

_&&&

3.4.3 Number of Full Load Cycles Based on Class of Crane The number of full load cycles from the CMAA fatigue criteria for crane design is listed in Table 3.2.

These criteria cannot be applied directly to a supporting structure. Issues that must be considered are:(a) span lengths of the supporting structure compared to the crane wheel spacing. (b) the number of spans over which the crane operates. For instance, if the crane operates randomly over x

spans, the equivalent number of full load cycles for each span might be more like the number of cycles above, divided by x. On the other hand, in a production type operation, each span on one side of the runway may be subjected to almost the same number of full load cycles as the crane is designed for if the crane travels the length of the runway fully loaded each time.

(c) the number of cranes. (d) over or under utilization of the crane with respect to its class.

15

For Class of Crane Service A, B, or C where the lifting operation is randomly distributed along the length of the runway beams and across the crane bridge, it is suggested that the number of cycles of loading of varying amplitude for components of the crane-supporting structure can be estimated as the number of full load cycles for the class of crane divided by the number of spans and multiplied by the number of cranes, further provided that the life of the runway is the same as the life of the crane.

Table 3.2 &99*(,!0,0

!

! *(,!!0

A 100

B 200

C 500

D 800

E 2 000

F > 2 000

Table 3.3 "!/'!0!8!

! *(,!!0

A 0 to 100

B 20 to 100

C 20 to 500

D 100 to 2 000

E 500 to 2 000

F Greater than 2 000

The basis of selecting these numbers is not explained nor is it evident whether these are the total number of cycles or the equivalent number of full cycles (see Section 3.3.3).

16

For instance, the runway for a new Class C crane, 5 spans, would be designed for 100 000 cycles.

The suggested numbers of cycles for the design of the crane-supporting structure as a function of the class of crane vary widely among the sources. The basis of the recommendations is not clear. Fisher (2004), Fisher and Van de Pas (2001), and MBMA (2006) give the values shown in Table 3.3.

Table 3.4 presents the recommended number of cycles for the design of the crane-supporting structure based on

"

>Kby duty cycle analyses as presented in Section 3.4.4. Examples of the analyses are given in Section 3.5. N is &&Q/&>"

KQK

By comparing the recommended number of cycles in Table 3.4 to the number of cycles for the crane in Table 3.2,

"

'full load cycles for crane Classes A, B and C, and 50% for crane Classes D, E and F.

The information in Table 3.4 is not meant to take the place of a duty cycle analysis for the installation being investigated.

3.4.4 Fatigue Loading Criteria Based on Duty Cycle Analysis As discussed in Sections 3.4.1 and 3.4.3, a duty cycle analysis for one or more cranes will yield the spectrum of loading cycles for the crane-supporting structure. Note that only the results of the duty cycle analysis that are of interest to the structure designer are shown herein. To determine the location of the critical element of the structure and its loading spectrum requires a time and motion study beyond the scope of this document. Weaver (1985) and Millman (1996) provide examples of duty cycle analyses.

Table 3.4 "((*(,!0!8!

! Recommended

a*(,!!0*

SA 20

SB 40

SC 100

SD 400

SE 1 000

SF Greater than 2 000 b

a Used as a calibration of the supporting structure (Structural Class of Service) to class of crane service in Chapter 4. As is the case for the crane, the supporting structure will withstand many more cycles of varying amplitude loading.

X"&&&Z

17

After identifying the critical component of the structure and the equivalent number of full loading cycles, the fatigue design criteria for the structure can be prepared.

This is the most accurate and is the preferred method of determining the fatigue design criteria.

3.4.5 Preparation of Design Criteria Documentation The structural class of service for entry into Checklist Table 4.1 is determined from the duty cycle information or from previous procedures related to crane service class.

Refer also to Chapter 7 for other information that should be obtained for preparation of the design criteria.

+Z[8(>

80090Compute N, the equivalent number of full loading cycles for the location deemed most critical. This is the lower limit of N to be used in Table 4.1. For example, if N is calculated to be 500 000 cycles, go to Structural Class of Service SD. Use the actual numbers of cycles of loading from that point on. The spectrum of loading cycles for the critical elements of the structure should be included in the design criteria.

The design criteria statement for fatigue design might appear as follows:

The supporting structure will be designed for cyclic loading due to cranes for the loads as follows:

Load Level, % of Maximum Wheel Loads Number of Thousands of Cycles, N*

100 10

75 50

52 100

25 200

* Means number of passes of cranes.

Design for cyclic side thrust loading will be for 50% of each number of cycles above with the corresponding percentage of side thrust for cyclic loading.

18

+Z8(>

!;9,,=The design criteria statement for fatigue design might appear as follows:

The supporting structure will be designed for cyclic loading due to cranes for the following loads.

Load Level, % of Maximum Wheel Loads Number of Cycles, N*

100 40 000

* Means number of passes of cranes

Design for cyclic side thrust loading will be for 50% of the number of cycles above with the corresponding percentage of side thrust for cyclic loading.

Z/'(!80090

3.5.1 Crane-Carrying Steel Structures Structural Class Of Service SA, SB, SC A Class C crane operates over several spans (say 5 or 6). In accordance with the CMAA standards, the crane is designed for 500 000 cycles of full load, but only 50% of the lifts are at full capacity. The lifts are evenly distributed across the span of the crane bridge. The operation along the length of the runway has been studied and the conclusion is that no one span of the supporting structure is subjected to more than 250 000 cycles of a crane with load and 250 000 cycles of an unloaded crane. The loading spectrum for the critical member of the supporting structure is shown in Table 3.5.

,Z/'((!

9>\

!&'(( Wheel Loads *(,!0* Description

100 62 500 Fully loaded crane

80 62 500 *

60 62 500 *

40 62 500 *

30 250 000 Unloaded crane

* Loads and trolley positions vary.

19

The equivalent number of cycles at full wheel loads is calculated as follows:

. . . .cycles

N 62 500 62 500 0 8 0 6 0 4 250 000 0 3

62 500 49 500 6 750 118 750

3 3 3 3#= + + + +

= + + =

^ h

The supporting structure should be designed for, say, 120 000 full cycles.

118 750 cycles is 24% of the number of cycles that the crane is designed for.

The above duty cycle is probably more severe than most for these classes of cranes and this type of operation, so use 20% as the criterion. This should serve as a conservative assessment for most applications.

3.5.2 Crane-Carrying Steel Structures Structural Class of Service SD, SE, SF +

XK

>2 000 000 cycles of full load. In addition to the loaded cycles, the supporting structure will be subjected to an

Z &>

" " conclusion is that the loading spectrum for the critical member of the supporting structure is as follows:

The equivalent number of cycles at full wheel loads is calculated as shown in Table 3.6.

. . . .cycles

N 500 000 500 000 0 8 0 6 0 4 2 000 000 0 3

500 000 396 000 54 000 950 000

3 3 3 3#= + + + +

= + + =

^ h

The supporting structure should be designed for, say, 1 000 000 full cycles.

950 000 cycles is 48 % of the number of cycles that the crane is designed for.

The above duty cycle is probably more severe than most for these classes of cranes and this type of operation. Use 50 % as the criterion. This should serve as a conservative assessment for most applications.

,]/'((!

8/\

!&'(( Wheel Loads *(,!0* Description

100 500 000 Fully loaded crane

80 500 000 *

60 500 000 *

40 500 000 *

30 2 000 000 Unloaded crane

* Loads and trolley positions vary.

20

CHAPTER 4 - DESIGN AND CONSTRUCTION MEASURES CHECKLIST

4.1 General The checklist in Table 4.1, calibrated to structural class of service (see Section 3.4.3), has been prepared as a

recommendations. Runway beam refers to the runway beam or girder. Items that may be fatigue related

K

21

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

3. Brackets should not be used to support crane beams with unfactored reactions greater than about 250 kN.

r r r r r r

4. Building and crane support columns made up of two or more column sections should be tied together to act integrally. (f)

* * * r r r

5. Where crane columns and building support columns are not tied rigidly, the axial shortening of the crane-carrying columns should be accounted for. (f).

* * r r r

6. Where building bents share crane-induced lateral loads, a continuous horizontal bracing system should be provided at or above the crane runway level. (f)

r r r r r r

7. Use of diaphragm action of roof deck for crane-induced load sharing between bents not advisable. (f)

r r r r r r

8. Use of girts for lateral support for crane-carrying columns not advisable unless designed for cyclic loading. For Classes A, B and C, this provision need not apply to the building column if there is a separate crane-carrying column attached to the building column. (f)

* * r r r

9. Crane bridge tractive and bumper impact forces should be accounted for by the use of vertical bracing directly under the runway beams or by suitable horizontal bracing or diaphragm action to the adjacent building frame. The effects of torsion about the vertical axis of rigid frame members should be resisted by bracing.

r r r

'

& K& webs not advisable unless service loads can be accommodated without such action. (f)

r r r r

11. Eccentricities of crane-induced loads such as rails K below and weak-axis bending on columns should be accounted for.

r r r r r r

22

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

12. Side thrust from cranes should be distributed in proportion to the relative lateral stiffness of the structures supporting the rails.

r r r r r r

13. Structural analysis should account for three-dimensional effects such as distribution of crane-induced lateral loads between building bents.

r r r r r r

?K&crane loads, one crane only, not including impact, should not exceed the indicated ratios of the span.

r

6001

r

6001

r

6001

r

8001

r

10001

r

10001

*}$ ? K&

Q

ratios of the span.

r

4001

r

4001

r

4001

r

4001

r

4001

r

4001

[; ? K& level from unfactored crane loads or from the unfactored 1-in-10-yr wind load should not exceed base plate or 50 mm, whichever is less.

r

2401

r

2401

r

2401

r

4001

r

4001

r

4001

Exceptions for pendant-operated cranes are noted: The lesser of 1/100 or 50 mm

\Y ?

23

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

20. Where lateral restraint to runway beams is provided, the relative movements between the beam and the supporting structure should be accounted for. (f)

r r r r

21. Complete-joint-penetration welds with reinforcing should be provided at runway plate girder web-to-?

24

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

28. Intermediate stiffeners should be applied in pairs. (f) r r r

29. Detailing and installation of crane rails should be in accordance with generally accepted practice to limit wear and tear on the runway and cranes:

r r r r r r

|&?advisable. (f) r r r r

|K&K&"in accordance with the recommendations included herein unless previously agreed to the contrary. The runway should be inspected and accepted by the rail installer prior to installing rails.

r r r r r r

| r r r

30. Impact factors are applied to crane vertical wheel loads and should be applied to runway beams and their connections and connecting elements, including brackets, but excluding columns and foundations.

r r r r r r

31. Design of runway beams should account for gravity loads applied above the shear centre. r r r r r r

32. Use of slip-critical bolted connections for connections subjected to repeated loads or vibrations required. (f)

r r r r r r

33. Use of fully pretensioned high-strength bolts in all bracing and roof members advisable. (f) * * r r r

34. Use of snug-tight bolted connections for secondary members acceptable. (f) yes yes yes no no no

35. Use of elastomeric rail pad advisable. (f) * * *

25

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

36. Ratio of depth-to-web thickness of crane beam webs should not exceed: (f)

h tM S

1900

f

#z

r r r

37. Where web crippling may occur, web bearing stresses should be below yield and avoid the possibility of web buckling.

* * r r r

38. Use of rubber noses on rail clips advisable. (f) * * r r r

39. Use of welded rail splices advisable. (f) * * r r r

'?QK-tions of stiffeners, diaphragm connections and the like, should be accounted for in the design. (f)

* * r r r

41. Longitudinal struts to columns located below the crane runway beams should be designed for fatigue ?Q?of the runway beams. (f)

r r r

Items 42 to 53 cover, generally, but are not limited to, inspection and construction

42. Removal of shims before grouting base plates rec-ommended * * *

?K&

?"direction of axial or bending stress. (f)

* * r r r

26

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

44. Crane beams or trusses of spans greater than 20 m should be cambered for dead load plus 50% of live ?"K

r r r r r r

45. If top cover plates or cap channels are used, contact should be maintained across the section after welding. (f)

* * | r r r

46. Standards for Inspection and Quality of Welding for runway beams and their connections to the supporting structure should be as follows:

|K?should be radiographically or ultrasonically in-spected to the degree shown in percent. (f)

15 25 50 100 100 100

|K?

be radiographically or ultrasonically inspected to the degree shown in percent.

* * * 25 25 50

| complete - joint - penetration web - to - ?Kshould be ultrasonically inspected to the degree shown in percent. (f)

* * 50 100 100 100

|KK?K''inspected by liquid penetrant or magnetic particle inspection. (f)

r r r r

47. Special procedures for maintaining tolerances for

crane beams recommended.

* * r r r

48. Accumulated fabrication and erection tolerance for centring of crane rail over supporting beam should be such that the crane rail eccentricity shall not exceed three-fourths of the beam web thickness.

r r r r

27

,+[

Description

!One Crane Only

SA SB SC SD SE SF

!0

Q(^*_

20 40 100 400 1 000 Not

8

49. Unless otherwise agreed with the crane manufacturer, centre-to-centre distance of crane rails as constructed should not exceed the indicated distance in mm from the theoretical dimension at 20C.

r

10

r

10

r

10

r

8

r

6

r

6

50. Tops of adjacent runway beam ends should be level to within the distances shown in mm. 3 3 3 2 2 2

51. Crane runway beam bearings should be detailed, fabricated and assembled so that even bearing is /Q

1.0 mm. Any proposal for shimming should achieve the required tolerances and should be submitted to the designer for review. (f)

* * r r r

52. Flanges of crane runway beams, for a distance of 500 mm from their ends, should not be curved as viewed in cross section, and should be normal to the webs to within 1 mm in 300 mm.

r r r

53. Ends of rails at splices should be hardened and milled. (f) * * r r r

+((@Comments on the checklist in Table 4.1 are given in Table 4.2 on an item-by-item basis. Background information >

+;^''''&

&Zservice cranes, they are generally less stringent than for Classes C to F. There is a wide range of duty cycles for Class C but because severe problems have not been widespread historically, the recommendations are somewhat less severe than for Class D.

"been calibrated to a concept of a crane runway of several spans and with one crane on each runway. See Section 3.4.3 for details.

28

For all classes, the designer of the structure should advise the owner prior to completing the design if recommended measures are not intended to be implemented, along with reasons. For design-build projects, it is recommended KZ

Table 4.2 ((!@!8!

Item Comment See

2

Occasionally runway beams are designed as simple span but supplied in lengths that provide continuity over supports. Fisher (2004) and Rowswell (1987) provide information on this topic. The structure designer should consider the effect of settlement of supports, particularly for underslung cranes. The owner should be made aware of any proposal to provide continuity or cantilever construction, and the implications thereof.

-

3The recommended method for supporting crane runway beams is use of stepped columns KQ

;^&

of service D, E, and F.

1

4

The crane runway support is sometimes designed as a separate set of columns, beams, and longitudinal bracing, attached to the adjacent building support columns for lateral support of the runway and to reduce the unsupported length of crane runway carrying columns. This is acceptable if properly executed, taking into account movements such as shown in Figure 8. However, the interconnecting elements are occasionally subjected to unaccounted-for repeated forces and distortion-induced fatigue. Flexible connections are undesirable for the

1

8

5 Refer also to Item 4. The interconnecting elements and connections may be subject to distortion-induced fatigue. 8

6

For light-capacity cranes where building framing is relatively rugged, sharing of loads between building bents may not be required. Unless it can be shown that without help from roof diaphragm action, horizontal differential movement of adjacent columns due to crane side thrust or crane gravity loads is less than column spacing divided by 2 000, it is recommended that continuous horizontal bracing should be provided at roof level. In this K&"K

3

7This item does not preclude the use of metal deck to provide lateral support to compression ?horizontal bracing system for crane loads is in place.

-

8 This recommendation need not apply on light-duty structures. -

9 Refer to Fisher (2004) for additional information. -

10Clause 26.4.2 of S16-09 places a restriction on the h/w ratio under fatigue conditions. > & ^ & ^distortion fatigue conditions.

-

11 Several eccentricities should be considered. 5

29

,+

Item Comment See

13 Some degree of three-dimensional analysis is required to adequately assess loads in hori-zontal bracing. Refer to Fisher (2004) and Griggs (1976) for additional information. 3

14/15Y?#*K]++X??X

can cause serious problems and should be limited to 12 mm unless special measures are incorporated.

-

17

Q

&?Qin rail-to-rail distance, even under crane-induced gravity loads that cause sway of the structure. These movements can create crane operational problems and unaccounted-for lateral and torsional loads on the crane runway beams and their supports. Final runway alignment should be left until after the full dead load of the roof is in place.

1

18

For applications where the ambient temperature range lies between +150C and -30C, structural steel meeting the requirements of CSA G40.21 grade 350W can be expected to perform adequately. For service at elevated temperatures, changes in properties of the steel may warrant adjustment of design parameters. While notch toughness at low temperatures is often required by bridge codes, this is not usually a requirement for crane runway beams, one reason being the relatively small cost of replacement compared to a bridge beam.

-

19

Limiting restraint to rotation and prying action on bolts can often be accommodated by ?&KK

?to outside as shown in Figures 14 and 18. The cap plate thickness should be limited or use $&/eccentricity of vertical loads shown in Figure 18 may cause a state of tension in the column ?`"

&

struts should not be used, in particular for class of service C, D, E and F.

9 14 15 18

20Where lateral restraint is not provided, the runway beams should be designed for bending about both the strong and weak axes. See AISC (1993), Rowswell and Packer (1989), and Rowswell (1987).The use of details that are rigid in out-of-plane directions should be avoided. S16-01 requires consideration of the effects of distortion-induced fatigue.

13 14 15 16

21>K?K ?K"for instance. There is no directly applicable fatigue category. Refer to AISE (2003) for additional information.

5 10

24

K K& & + *! # K K categorically not allowed on dynamically loaded structures by some authorities such as AISE (2003) and AWS (1999). The use of these welds should be restricted to applications where fatigue is not a consideration.

-

30

,+

Item Comment See

26 The recommendations for contact bearing are similar to railroad bridge standards and are more stringent than for statically loaded structures.9 18

27 Y`&K

#KKwould occur on continuous beams. A method to allow realignment of the rail and supporting beam should be provided. Railway type, ASCE, or other rails of hardened material should not be welded to the supporting structure under any circumstance. Bolted splices should be staggered. Rail splices should not occur over ends of beams. See Fisher (2004) and AISE (2003) for more information on detailing practices. A gap should be provided between the end of the rail and the end stop to allow for thermal movement of the rail.

13 14 15 16 17 18

30The designer should review the complete connection that supports the runway beam for fatigue. Impact factors should be applied to cantilever brackets and for underslung cranes and monorails, to adjacent truss members and connections.

-

31 Refer to Section 5.9 and the CISC commentary on S16-09. 5 6

32

S16-09, Clause 22.2.2 provides requirements for use of pretensioned bolts and slip-critical connections. Some judgement on the part of the designer is required to determine whether the fatigue loads warrant slip-critical connections for all main and secondary members, particularly where structural integrity would not be compromised. Slip-critical connections KK&Z

bolts with burred threads or welded nuts is not recommended for connections subject to fatigue but may be considered, however, for lighter duty structures such as shown in Figures 14 and 15.

-

33 Bolts have come loose due to vibration and dropped, causing not only weakened connections, but also a safety hazard. -

34 Snug-tight bolts are acceptable in light-duty applications for roof members, girts, and the like. -

35 Elastomeric bearing pads have been shown to reduce noise, increase rail life, and reduce

K?K& 19

36 From AISE (2003) and S16-09. -

37 See Item 9. -

31

,+

Item Comment See

38Rubber nosings have been shown to reduce failures of rail clips due to uplift from bow wave effect while at the same time resisting uplift. Rubber nosings should be used with elastomeric rail pads.

19

39

+&KK"

ZKwelded splices include noise reduction, impact reduction and reduced wheel wear. Welded rail splices should be used with elastomeric rail pads. This measure provides continuity and avoids pinch points.

-

40 ]&?Q 10 19

41 +?K&?Q"imposed on struts beneath it. 9

42There is no general agreement, but shims left in place are reported to have caused splitting of the concrete beneath. Levelling screws are always an option and are recommended for large loose base plates. The usual method of removing shims is to leave edges exposed and &

-

43 Only experienced operators should do this work and caution must be exercised to avoid notching the parent metal, particularly at tapers and changes in plate thickness. 25

45

?K

K?"Kforces that can cause premature cracking. The criteria for contact should be considered similar to that contained in Clause 28.5 of S16-09.

-

46

This item should be read in conjunction with requirements for welding details. A discontinuity K^in the parent metal. Failure of any NDT test in a tension zone should lead to 100% testing of all tension area welds. Failure of the test in a compressive zone should result in testing double the recommended percentage.

25

47 See Section 5.27, Fisher (2004), ASCE (2002), and AISE (2003) for additional informa-tion. 24

48The effect of rail eccentricity from the centre line of the runway beam web beneath under repeated loads can lead to premature failure due to unaccounted-for torsional loads. Refer to Item 21, Section 5.28 and the references for more information.

5

49 This tolerance is subject to review by the crane manufacturer and the structure designer and may be increased, depending on the rail-to-rail distance and the crane wheel design. 24

51 See Item 266 16 18

52 To provide proper bearing and to keep webs vertical and in line. -

32

CHAPTER 5 - OTHER TOPICS

5.1 General

>

?&]&

Z#&(>Obviously the crane itself and the supporting structure interact. The extent to which the structural designer takes this into account is a matter of judgement. That the crane bridge ties the two crane rails together is acknowledged when the transverse lateral forces due to trolley accelerations or to picking the load up non-vertically are distributed to the two crane rails in proportion to the lateral stiffness of the supporting structure. It is only necessary that friction ?K

#Kof the structure under other load combinations provided only that the frictional force exceeds the appropriate

A second factor to consider is that the dead weight of the crane may not be distributed symmetrically either transversely or longitudinally resulting in heavier wheel loads on one rail than the other or loads distributed non-uniformly along one rail from front to back. Be that as it may, pairs of crane wheels are usually articulated such that the vertical loads within the pair on a side are equal while multiple articulations increase the number of wheels with nominally equal loads.

Beyond this, however, the transverse stiffness of the crane end truck assemblies can affect the distribution of the lateral forces to the rails. Keep in mind that the function of the truck assemblies is to distribute the load to the wheels. In buildings such as mill buildings, heavy-duty cranes with several sets of wheels may have a wheelbase longer than the bay spacing. The crane does not simply impose a set of independent wheel loads on the structure because the end assembly may have a lateral stiffness comparable to that of the crane runway beam. It is not a question of a wind or other such load, with no structure behind it, which follows the structure as it deforms. ;K&?^

&K

K

against the hard spots. While common practice has been historically not to take this into account, the assessment &KQQ&`Qthe end truck assembly may in fact supply some continuity from span to span for transverse loads even when the lateral stiffening trusses are not continuous. Note!"

forces necessary for the two elements being bent to act together.

5.3 Clearances

Every crane requires operating space that must be kept free of obstructions. The layout of an industrial building with overhead cranes must be developed in conjunction with this envelope. AISE (2003), CMAA (2010), MBMA (2006) and Weaver (1985) provide blank clearance diagrams. Problem areas that have been encountered are:

cranes fouling with building frame knee braces, K"?

and structural connections not shown on the design drawings, K&"

33

Z+&!90At the very least second-order elastic methods of analysis should be used for structures covered by this design guide in keeping with the philosophy of S16-09. Plastic design methods are not recommended except perhaps for K?&

Use of computerized structural modelling with proven software to account for sway effects, P-, instead of the more approximate methods of Clause 8.7.1 of S16-09 are recommended. Commonly used computer software is easily capable of not only doing second-order elastic analysis, but by adding joints along the length of compression members subject to bending; the P- effects (Clause 13.8.4 of S16-09) are generated along with the P- effects.

& > Qshould be able to isolate critical load combinations and thus reduce the number of load combinations that require a second-order analysis.

5.5 Notional Loads S16-09 requires use of notional loads to assess stability effects (Clause 8.7.2). This approach is somewhat different from AISE and AISC methods where effective lengths using the well known but approximate elastic

>

K^/

"^in S16-09 as a small percentage (0.5%) of the factored gravity loads at each storey of the structure. The translational load effects thus generated (otherwise there might be no lateral load) transform the sway buckling or bifurcation problem to an in-plane strength problem. There is no need to consider effective length factors greater than one.

The use of notional loads applied to a crane-supporting structure requires considerations beyond those usually encountered in residential or commercial construction because lateral loads are applied at the crane runway beam >&&effective and equivalent lengths as applied to stepped columns requires steps in the analysis and design that are not well covered in commonly used design aids.

MacCrimmon and Kennedy (1997) provide more detailed information and a worked example is presented. See also Section 5.6.

Z]((&&K?K&building with expansion joints is complex. Experience has shown that these installations usually perform well K?Q

>along the length of the runway, and adjustments may be necessary.

For more information, see Fisher (2004).

Zg>/'jDistance between expansion joints, in general, should not exceed 150 m. Use of double columns is recommended over sliding joints, particularly where design for fatigue is required and for Crane Service

`"

`

35

A design method in accordance with S16-09 follows and is used in Appendix A, Design Example 1.

5.9.1 Design Method A rational method for calculating the factored moment resistance of a laterally unsupported beam, similar to the method proposed by Ellifritt and Lue (1998) and in accordance with S16-09 is as follows:

Referring to the typical moment resistance diagram above for unbraced lengths, the portion of the curve for the intermediate or inelastic range is reasonably close to a straight line. S16-09 uses a straight line transition from the elastic buckling curve at Mu = Myr , L = Lyr to Mu = Mp , L = Lp .Establish the class of section in bending and determine if the limiting strength may be governed by the yield stress or by local ?K^

For L L M Mu u p =, (plastic region)

For L L Lu yr< (inelastic region)

The unfactored moment resistance for simply supported beams under uniform moment, loaded at the shear centre, can be determined by the following formula:

M M M M L LL L

Mr p p yr uyr u

p= ( )

For L L M Myr r u> =, (elastic region)

Note that Lyr cannot be calculated directly and must be solved by trial and error iteration until the unbraced length used in the formula for Mu produces a moment Mu = Myr. That length is then Lyr.The general formula for Mu , the critical elastic moment of the unbraced mono-symmetric beam, is given in S16-09, Clause 13.6(e)(ii):

MEI

LGJ L

E ICIu

yx x

y

w

y= + + +

3

2

22

2

224

&(!,

]&

]

&

36

x , Cw and J can be calculated using information from the Technical Resources at the CISC website for calculating torsional sectional properties. Refer also to Design Example 1, step 12.

Myr = 0.7 Sx Fy with Sx taken as the smaller of the two potential values Lyr = length L obtained by setting Mu = Myr

L r E F r

Fu t yt

y 1 1 490.

where:

r b

h wb t

tc

c

c c

=

+

12 1 3

where:

hc = depth of the web in compression bc K

? tc ^

?

Z[q>'>Crane runway beams subject to biaxial bending are proportioned in accordance with Clause 13.8.3 of S16-09, which when the axial compression is zero, gives

MM

MM

fx

rx

fy

ry+ 1 0.

The capacity of the member is examined for (a) overall member strength, and (b) lateral-torsional buckling strength. It is noted that this formulation requires lateral-torsional buckling about the strong axis to be considered as appropriate and allows inelastic action to be considered provided that the width-thickness ratios of the elements &^&

See Appendix A, Design Examples 1 and 2.

37

Z[[?0A commonly encountered detail involving what is commonly referred to as an apron plate is shown in Figure 7, along with recommendations based on S16-09. The designer should refer also to Clause 11.2 and Table 2 of S16-09 for criteria for maximum width-to-thickness ratios. The design of such members for horizontal strength is usually done by rational analysis if the section that resists lateral forces is of reasonable depth (say about span/15 minimum) and can function as a web-horizontal beam. See Design Example 2 in Appendix A. Web crippling and yielding under concentrated wheel loads is covered in S16-09, Clause 14.3.2. In accordance with AISE 2003 and CMAA 2010, the concentrated wheel load is distributed at 1:1 from the top of the rail to the contact surface at the top of the beam. Canadian practice and the calculation in Example 2 suggest that a slope of 2.5H to 1V is appropriate.Referring to Figure 5, crane load eccentricities can cause local out-of-plane bending in the web. An exact analysis is complex. DIN, Australian Standards, and work by Cornell University address this topic. Rowswell (1987) notes that AISE does not take into account the wheel load acting off the centre of the web, or the tilt of the beam

"

&

?Q&Q&

?Q&&&&

"&^K"

"&KKK ? K _

KKK?It is recommended that local torsional effects be examined for welded sections. See Appendix A, Design Example 2 for typical calculations. For crane runway beams, including welded sections, it is not common practice to check interaction of out-of-plane

K?"

Qand because of experience in the industry. More research on this topic is needed. Additional recommendations for large, heavy-duty crane runway girders with apron plates as one would encounter in steelmaking facilities are given by Fisher (2004), AISE (2003) and Rowswell (1987). Some references show a calculation of local wheel support stresses based on older editions of AISE Technical Report No.13. This is no longer recommended and is not included in AISE (2003). A bearing detail that has been used successfully is shown in Figure 20. This detail can reduce eccentricities, facilitates achieving tolerances in squareness and elevation, and reduces restraints at beam bearings. As noted in Chapter 4, special measures are usually implemented to control shop and erection tolerances.

Z[#(),!!

For longer spans and heavier installations, a decision often must be made whether to use partial or full-depth intermediate web stiffeners (see Figure 19) or to use a thicker web and avoid the use of these stiffeners. Partial-K?

?"K^resist torsional forces. Structures of each type have been providing satisfactory service. If weight is not the governing factor, many experienced designers would agree that a thicker web without intermediate stiffeners is

&"K?"fatigue in the tension zone of the web and distortion-induced to fatigue.

Use of horizontal web stiffeners as for highway bridges is not common and is not recommended for new construction for the same reasons as noted above. These stiffeners may be part of a solution for upgrading, however. Caution must be exercised in zones of tension, particularly at splices in the stiffeners. If the stiffeners are not butt welded full strength and ground in the direction of stress, a fatigue crack might propagate into the web.

Z[@"Q0>(To accommodate differential longitudinal and vertical movements between the crane runway beam and supporting structure, but at the same time to provide lateral restraint to the beam, articulated links are often provided for

ZK&

the individual standards permit.

#

?K

!\['!

K"the more stringent requirements should govern.

^&&Q

"+

"&&-quired.

Zk!#Refer also to Sections 5.27 and 5.28.

Figure 25 shows commonly used standards for welding and inspection of crane runway beams.

See W59 for more information.

Y+*!"$to CSA Standards W178 and W178.2 respectively. For inspection of other aspects of fabrication and erection, Q#&KZK " Z dynamically loaded structures as may be applicable.

+;[\![Z""*

&structure. The user is advised to consult with the jurisdiction having authority regarding adoption of this Standard, and whether there may be exemptions or additions.

5.30 Maintenance and Repair Crane-carrying structures subjected to fatigue, in combination with:

age, unintended use (often called abuse), inadequate design, imperfections in materials, substandard fabrication, substandard erection methods, and building component movements, such as foundations,

require maintenance and repair. Repair procedures should incorporate the recommendations of an experienced structure designer, or the repair can create effects that are more serious that the original imperfection.

Referring also to item 5.29, it is recommended that periodic inspection and maintenance be done and a checklist should be prepared for the maintenance personnel.

Fisher (2004), Millman (1991, 1996) and Reemsnyder and Demo (1978) provide additional information.

43

CHAPTER 6 - REHABILITATION AND UPGRADING OF EXISTING CRANE-CARRYING STEEL STRUCTURES

6.1 General Designers may be asked to assess and report on the condition of a crane-carrying steel structure for different reasons such as:

concern about the condition of the structure, due diligence brought on by a change in ownership, to extend the useful life under the same operating conditions, to increase production by adding cranes or other equipment, and to modify processes and add new and possibly heavier cranes or other equipment.

The structure may be several decades old, materials of construction are not clear, drawings and calculations are nonexistent, and past crane duty cycles unknown. The local building code authority may be unprepared to accept measures which might be interpreted as contrary to the provisions of the local building code.

Little guidance is available that is directly related to crane-carrying structures in Canada. AISE (2003) and Millman (1991) provide guidance and are the basis of several of the recommendations contained herein. AISE (2003) provides an appendix that addresses recommended practices for inspecting and upgrading of existing mill building structures. Note that the NBCC Commentary contains relevant information.

]#0"An inspection plan should be prepared that is based on the following as a minimum:

site visits, KQK""""" Z" interviews with plant personnel, to gain insight into the operation, past and present, and review of the applicable codes and standards.

> &

& & following:

visual inspection noting defects such as corrosion, cracks, missing components, reduction of area, detrimental effects of welding, and physical damage,

visual inspection of crane rails and their connections, visual inspection of connections, K" comments on misalignments and settlement, including need for an alignment survey, and special investigations such as identifying older steel, weldability, nondestructive testing, measurements of

K

"""?"and thermal loads.

A common problem when evaluating older structures is to identify older steel. S16-01 covers this in Clause 5.2.

>

"as a minimum, are as follows:

background, including purpose of the inspection, scope, available records, records of discussions,

44

general description of the structure, " history of the use of the structure, including crane duty cycles, history of performance and maintenan